Why Monkeys in the Middle Are More Stressed

Study on macaques helps explain why human middle managers have the most stress.

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Japanese macaques relax in a hot spring.

Photograph by Tim Laman, National Geographic

Being a monkey in the middle is pretty much like being a middle manager: According to a new study, stress levels for macaques in the middle of a tribe's hierarchy are likely to be higher than those of their counterparts at the lower end of the social ladder.

Researchers monitored nine female Barbary macaques for nearly 600 hours and found that the middle-ranking individuals had higher levels of stress hormones in their fecal sample than the others. And human middle managers are likely to suffer a similar degree of stress.

"Although the particular challenges that humans face might be different [from] those seen in other species, the underlying physiology is similar," lead author Katie Edwards of the University of Liverpool wrote in an email. "The idea remains that individuals in the middle of the hierarchy have to contend with challenges from above and below."

Other macaque observers agree that life is no picnic for middle monkeys. "The stress for macaques, like humans, is not so much about getting the goodies within the hierarchy. It's about how others relate to me and how I relate to others," said National Geographic explorer Agustin Fuentes, who was not involved in the study but has been observing macaques in Singapore's urban jungles using Crittercam.

Fuentes, who teaches human evolution and behavior at the University of Notre Dame, added that middle-ranking individuals are under more stress because their interactions are less predictable. "They're not exactly sure how others are going to respond to them and how they should respond to others." He was talking about macaques. But he might as well have been analyzing human middle managers.

Dealing With the Stress

So how do macaques deal with their stress? Here are some of the ways. Middle manager humans, feel free to try these out.

Hang out with a baby. A common stress reliever among macaques is taking care of infants. Both males and females love spending time with younger members of the troop, whether their own infant or someone else's. Grooming babies is a relaxing pastime. "They will grab [an infant] and take it over to their friends and groom it together," Fuentes said. "And that helps them calm down." Warning to middle managers: Taken to excess, this behavior could lead you to audition for "Toddlers and Tiaras."

Grooming and scratching. "Grooming can relax both the individual grooming and the one being groomed," Fuentes said, adding that grooming a friend is similar to how humans pet their cats or dogs when they come home from a long day. Similarly, macaques scratch themselves more if they are stressed, perhaps, he said, because the repetitive physical action is also a calming factor. Note to middle managers: Close office door before scratching.

Hug it out. A stressed-out macaque will seek an individual within their network for companionship. Female macaques, who tend to stay close to their relatives, will go to their mother to be embraced. One female, Edwards reported, spent more time embracing another monkey when her level of stress hormones was high.

Punch something. Macaques rarely engage in a serious fight over resources like food, grooming partners, or infants. But Edwards notes that stressed-out macaques will show aggressive behavior to warn another monkey that is causing a problem. "An individual will give an open-mouthed threat as a warning first," she said. "If that is ignored, this may be accompanied by slapping the ground and finally chasing the opponent." Humans might want to try a punching bag instead.